In a manufacturing process of a semiconductor device, a film called a sacrificial film may be used in some cases. The sacrificial film is a film used in the manufacturing process and removed in the middle of the manufacturing process so that the film is not included in a semiconductor device as a product. Examples of the sacrificial film include an intermediate mask formed on the lower layer side of a resist mask in a corresponding relationship with the resist mask, an intermediate film used for separating a trench and a via hole in a dual damascene, and the like. As the sacrificial films, suitable films are selected from various film materials such as inorganic films and organic films in consideration of the intended use thereof and the like.
The sacrificial film used in a predetermined manufacturing process is removed by dry etching that makes use of a plasma etching gas, wet etching that makes use of an etching solution, or the like. Meanwhile, an opening such as a trench, a via hole or the like may be formed on the surface of a semiconductor device (hereinafter also referred to as “structure”) in the middle of manufacture after using the sacrificial film. If an etching gas or an etching solution (collectively referred to as “etchant”) enters the structure through the opening, there is a possibility that a member existing inside the structure comes into contact with the etchant and suffers from damage such as deterioration or the like.
For example, there is available a technique of forming a via hole in a silicon layer using an etching mask corresponding to a sacrificial film and then embedding a protective portion made of a material such as polyimide resin, organic SOG, photosensitive resist or the like in the via hole.
The technique of the related art prevents hydrofluoric acid, hot phosphoric acid or the like used for removing an etching mask from entering the via hole by using the protective portion. However, the protective part itself is also ultimately removed from the semiconductor device which is a product. Therefore, there is also a possibility of causing damage to the interior of the structure in the process of removing the protective portion.